ISTANBUL - Turkish police released Monday a man who claimed he was plotting to kill U.S.President Barack Obama. (UPDATED)

The suspect was detained in Istanbul last week after police received a tip-off that he planned to attack Obama, who began a two-day visit here on Sunday, the source told AFP on condition of anonymity.
Police established that he was mentally disturbed and has since released him on the grounds that he would not pose a danger to Obama, the source added.
As standard procedure involving a threat against the president overseas, the Secret Service is following up with Turkish authorities regarding the case, Secret Service spokesman Ed Donovan said, adding that the president was never in any immediate danger and that details of the suspect would not be released.
White House spokesman Robert Gibbs, who was with Obama in Istanbul on Tuesday, declined to comment on the incident